Spring support assemblies are commonly used on devices such as swivel, or loading or unloading arms, that are used to assist in the transfer of various materials, both wet or dry, from a supply source to a container, tanker car or truck in which material are transported or shipped. Often, loading arms can be quite heavy and can be of considerable length. A spring support assembly generally provides a counterbalance force making it easier to move (e.g., vertically) the loading arm, and align it with the relatively small opening of a container. Since at times a loading arm needs to be handled by a single operator, it is preferable and desired to provide a counterbalance mechanism or assembly that will assist in rapid, easy and accurate placement of the end of the loading arm. Moreover, such counterbalance arrangements also need to be adjustable to properly install, set-up, adapt and/or maintain an arrangement in optimal condition for the particular situation.
One example of a prior spring balance assembly is shown in U.S. Pat. No. 3,038,714 to Klaus, et al. The spring tension can therefore be adjusted (e.g., increased or decreased) by either counter-clockwise or clockwise rotational movement of a spring regulator. This design allows the coil spring to be either tightened or loosened to the degree necessary to sufficiently support or position a loading arm. Some of the prior spring assembly, such as illustrated and disclosed in Klaus, et al., have several shortcomings. For example, to adjust or readjust the spring tension, the loading arm must be supported independently, typically by a crane or other device in order to decouple the loading arm and relieve the spring of its load. Next, a spring keeper must be removed (e.g., manually) from engagement with the spring regulator so that it and the end of the spring can be rotatably adjusted. When the desired position is achieved, the spring keeper is manually inserted back into engagement with the spring regulator so that it does not move. Thereafter, the loading arm is released for normal operations.
In addition to being inconvenient and labor intensive, this complex process of spring tension adjustment can lead to further difficulties in adjusting the spring tension. For example, this apparatus is not reliable, and often requires many "trial and error" attempts to achieve the desired spring tension. Each time the spring tension needs to be adjusted, the above discussed procedures must be followed, which can be cumbersome, time consuming, and typically requires more than one person.
Another prior spring assembly unit, for example, as seen in U.S. Pat. No. 4,537,233 to Vroonland, et al., had a protectively covered spring torsion unit with an assembly of a threaded adjustment screw and barrel nut. In use, the bolt theoretically could be rotated to adjust (e.g., increase or decrease) the spring tension, as the barrel nut moves laterally and alters its effective length along the bolt. As with other prior torsion spring units or assemblies, however, the unit in Vroonland nevertheless still practically requires either a structure for supporting the loading arm, or otherwise maintaining the loading arm in a substantially vertical position in order to relieve the spring coil of its load while the spring tension is being set or adjusted. Attempts to adjust the spring tension by rotating the bolt without supporting the loading arm could easily strip the threads of the adjustment screw, and cause the adjustment unit to fail. Furthermore, the barrel nut moves relative to and laterally along the bolt; and thus, the threaded screw assembly limits rotational movement of a spring regulator to a reduced radial distance.
Often over time, the complexity, difficulties and inconvenience involved in often retensioning the spring sometimes leads to foregoing of this retensioning procedure. As the spring can fatigue and lose its resiliency over time, and therefore the available counterbalancing spring tension is diminished, adjustment and retensioning can be important to maintaining desired optimal functional characteristics of a system. As a result of improperly tensioned arrangements, the loading arm can be inconvenient to utilize, and in some extreme situations, many end up resting on the ground between uses.
As can be appreciated, currently available torsion spring balancing units for counterbalancing a loading arm have a number of shortcomings that contribute to the complexity of the assemblies, difficulty in resetting or adjusting the spring tension, and overall reliability and usefulness of the loading arm equipment in general. There exists a continuing need in the industry for a torsion spring balancing unit that can be adjusted accurately and quickly without otherwise relieving the spring tension while the loading arm is in any position. It is also desirable to provide an improved adjustment assembly that eliminates many of the labor intensive steps currently involved in spring tension set up or adjustment.